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GRAPHICS
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IMAGE165.SPK
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!Image
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1995-05-29
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Introduction to Image
---------------------
Image is an image processing package which allows many varied
operations to be carried out on pictures. Within Image the emphasis
has been on power rather than ease of use, and as such it does take a
little getting used to - but it does have a fully graphical user
interface which is moderately easy to use once you have read the
instructions.
Image can load pictures in various formats, currently including most
sprite formats (including the new 15 and 24 bit sprites), clear files,
PBMPlus, GIF, TIFF, JPEG files, BMP and its own format (ImagePic) files.
Image holds pictures internally with full 24 bit accuracy, thus when
performing a series of operations the losses involved are minimal. The
problem with holding pictures in full 24 bit is that of size, a full
colour picture can require a large amount of memory to store it. For
this reason Image holds the internal picture on disc, reading portions
into memory when needed.
In fact Image can hold up to 8 pictures internally at any one time,
through the use of 'Image Banks'. Essentially Image uses 2 banks at
any one time, an input bank and an output bank. Most operations
operate by reading the input bank, performing some operation and
writing to the output bank. After the operation the input and output
banks are swapped over (thus a further operation will be performed on
the result of the previous operation). See 'Image Banks' for more
details.
Given the fact that Image stores internal pictures on disc, it is thus
necessary to have enough disc space available to Image to be able to
store these files. It is thus almost necessary to run Image from a
hard drive (with at least a couple of Meg free). By default Image
stores the pictures within its own application directory, but this can
be altered if necessary (see Configuration for details).
So that you can see the results of operations, Image has a display
window which shows the result of the last operation (the current input
image bank). Obviously this display window can not show the picture in
full 24 bit accuracy (current hardware does not support this, except
Risc PCs), instead it shows (by default) a 256 colour representation. This
256 colour representation is stored within memory (as a sprite) and can be
saved (see 'Loading and Saving'). However with a large picture the 256 colour
sprite can take up quite a bit of memory, thus it is possible to reduce this
sprite to a 16, 4 or even 2 colour sprite (see 'Configuration' for details).
Image also supports an 'Image Mask' which is slightly different to the
mask in a sprite. When an area of a picture is masked out all (except
a few) operations performed on that picture will only take effect on
the regions not masked out (masked areas are preserved as before).
Masks can easily be created and removed (see 'Merge Operations' for
details).
The operations available to image are varied, and are divided into
groups, each group having its own control window (each accessible from
the main 'Control Panel').
The first group of operations are colour control operations. These
affect colours within a picture, for example brightening, darkening,
inverting, etc. These operations are described in the 'Colour Control'
section.
The second group of operations are 'Kernel' operations. These are
powerful operations which perform functions such as sharpening,
softening, noise removal, etc. These operations are described in
detail in the 'Kernels Introduction' section, and the control window
is described in 'Kernel Control'.
The third group of operations are those of resizing a picture. Image
can resize in various ways, scaling, centralization, cropping,
tiling, etc. These are described in detail in 'Resizing Images'.
The fourth group of operations are those of rotation. Image can rotate
a picture through any angle, and about any point (even a point outside
the picture). It can also produce a 'spiral' where the angle of
rotation varies depending on the distance from the centre of rotation.
It can also perform plain rotations about 90, 180 and 270 and also
flips in both horizontal and vertical directions. See 'Rotating
Images' for details.
A fifth group is that of operations to merge pictures and also
create/alter/delete image masks. These are detailed in 'Merge
Operations'.
Image also allows you to alter pictures by painting over them. The way
this works is a little odd, and takes time to get used to, but it can
be very useful. How it works is that when you want to paint Image
creates what is called an 'overlay' image. This is, in fact, a 16
colour sprite which sits in the display window over the main picture.
Now what happens is that you paint into this sprite (using various
brushes) but none of this actually affects the picture in any way.
When you are happy with it, you can then 'merge' the overlay with the
picture (using any of the 'Merge' operations in group 5). More details
of this are given in the 'Paint' section.
One real advantage of Image using disc to store the internal copies of
pictures is that if for any reason Image crashes, your machine
crashes or there is a power cut you will not have lost very much (in
fact the most you will lose is the results of any half completed
operation).
One thing you will notice about Image is that if you select 'Quit'
from its main menu, it will never ask you to confirm the action. The
reason for this is that it is not necessary. As with crashes,
accidental (or for that matter non accidental) quits from the program
do not matter.
Recovery after a crash or accidental quit
-----------------------------------------
If you suffer a crash, or quit accidentally, simply re-run Image (at
any time, even after a reset) and bring up the main menu. On the menu
you will find an option marked 'Recover'. Selecting this option will
cause Image to scan its working directory to see what is available. It
will then bring up the 'Image Bank' control window which will contain
information about banks which contain pictures - all you need to do
now is go through the available banks seeing what is there.
The recovery operation should work in 99% of cases, allowing you to go back
to where you left off (or to the start of the previous operation if a crash
happens during an operation).